By Andrew Quinn
ISLAMABAD/KABUL (Reuters) - Secretary of State Hillary Clinton landed in Islamabad on Thursday to deliver a tough warning to Pakistan to cut suspected ties with militant groups which have severely strained ties between the uneasy allies.
Clinton, arriving from the Afghan capital, Kabul, left directly for the U.S. embassy and was scheduled to attend a dinner with senior Pakistani officials.
Clinton will be joined for talks by new CIA director David Petraeus and the Chairman of the Joint Chiefs of Staff, General Martin Dempsey, a clear sign that Washington is determined to get its message across.
In Kabul, she used a news conference to send a "clear, unequivocal message" to Pakistan saying it should help efforts to broker an end to the decade-long war in Afghanistan.
"They must be part of the solution and that means ridding their own country of terrorists who kill their own people and cross the border to kill in Afghanistan," Clinton said.
"We're going to be fighting, we're going to be talking and we're going to be building. And they can either be helping or hindering, but we are not going to stop our efforts."
Pakistani analysts agreed that Clinton would be sending a tough message to Pakistan.
"I think they've decided that they want to have a final word about the Pakistan-U.S. relationship, especially with reference to Afghanistan," said Tanvir Ahmed Khan, Pakistani foreign secretary from 1989-90.
The addition of Petraeus could be especially significant, said political analyst Hasan Askari Rizvi.
"America will produce evidence before the army chief, that you are involved (in supporting the violence in Afghanistan). With David Petraeus coming as well, they have definitely brought evidence," he said.
"He will provide evidence that you are involved, ISI is involved," he added, referring to Pakistan's Directorate of Inter-Services Intelligence, its powerful spy agency. "But nothing will come out in public."
Clinton's visit to Pakistan, which had not been announced due to security concerns, comes at a tricky moment in relations between Washington and Islamabad following charges by U.S. officials that Pakistan is playing a double game with militants who operate on both sides of the Afghan-Pakistan border.
U.S. and Afghan officials have drawn links between elements within Pakistan and both September's 20-hour attack on the U.S. embassy in Kabul and days later the assassination of Afghanistan's top peace envoy.
The tensions have complicated the outlook as the Obama administration pushes ahead with plans to draw down troops and hand security control to Afghan forces by the end of 2014.
U.S. officials had earlier said Clinton would seek to strike a constructive tone in discussions with Pakistani leaders, who have strongly denied backing insurgents and accused the United States of ignoring Pakistan's own interests in the battle against militants.
But Clinton on Thursday took a clearly combative tone, saying Islamabad had a choice to make. "It is a time for clarity. It is a time for people to declare themselves as to how we are going to work together," she said.
Clinton said the United States still believed it would be possible to reach a political solution to the decade-old conflict in Afghanistan and repeated that the Taliban should agree to enter the non-violent political process or faced "continued assault" from the U.S.-led alliance.
"Reconciliation is still possible. Indeed, it represents the best hope for Afghanistan and the region. But success will take an inclusive national dialogue and sustained political (support), including from Afghanistan's neighbors," she said.
Karzai, for his part, said the focus of the Afghan peace effort would now be Pakistan -- which he said effectively controlled the militants and provided them with safe havens from which to launch their attacks.
"Unless we pay attention to sanctuaries, and unless we go to the proper authority that leads and controls all that, we will not be able to have either a successful peace process or a successful campaign against terrorism," he said.
Clinton, too, focused on militant safe havens in Pakistan, saying it was time "to turn with real intensity to the safe havens within Pakistan," including those allegedly used by the Haqqani network, one of the most feared of such groups.
"Now it is a question how much cooperation Pakistan will provide going after those safe havens," she said.
Clinton's visit to Pakistan comes a day after army chief General Ashfaq Kayani told parliament's defense committee the United States should focus on stabilizing Afghanistan instead of pushing Pakistan to attack the Haqqanis in the border region.
"The problem lies in Afghanistan, not Pakistan," a committee member told Reuters on Wednesday, quoting Kayani. The MP spoke on condition of anonymity.
Pakistan's powerful military, which sets security and foreign policy, has been reluctant to attack the border region of North Waziristan, saying it was stretched fighting homegrown Taliban fighters elsewhere in Pakistan.
Pakistani paramilitary forces killed 34 Taliban militants in clashes in the restive tribal region on the Afghan border on Thursday, the military said.
There was no independent confirmation of the death toll. The Taliban movement, the biggest security threat to Pakistan, often disputes official death tolls on clashes.
(Additional reporting by Mirwais Harooni in Kabul, and Qasim Nauman and Zeeshan Haider in Islamabad; Editing by Chris Allbritton)